Steve the idea that the bar should be kept high because people then view them as skewed if a small majority vote for change doesn't really satisfy people either though. You just end up making the opposing side feel even more aggrieved. The best example of that was the first Scottish devolution referendum. The Yes side narrowly won the vote but not the referendum itself because the then Labour gvt put the bar higher than 50% of the turnout. It only bred resentment and left half the country feeling the democratic rights of the majority (albeit a small majority) were being ignored by Westminster.